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Topic: Engine/propeller hub puller (Read 1742 times)

Having had some challenges pulling propeller hubs off of crankshafts I started thinking about making a proper puller then I spotted a couple of items on Fleabay that might do the job. So I brought both to try them out...

This is the first one: For the vast sum of £5.99 in the UK and even cheaper from China, this one is nice . I might want to use a ball bearing on the end of the crank

The second one has arrive courtesy of Fleabay. This is slightly smaller and I think complements the much larger one. There is no way it is going to fit around the Atom Minor hub but it fits nicely around the end of the crankshaft casting for this Miget crankcase casting I found lying on the Dining room table

I was surprised to find that the silver pulling bracket is made out of steel on this little one so it can be modified if required

We used to use those (predominantly battery post) claw type pullers on larger RC engines. If they work, they work. But sometimes, depending on the drive washer shape & dimensional thickness, the claws would mar or even risk distorting the flange if its thin-ish. The lower pic you show with a 'U' shaped puller 'plate' spreads the load out a bit more so are preferable on that basis, even if you have to make your own custom one to fit properly. Sometimes the sticking is aggravated by baked fuel/oil/whatever that acts as effective glue. Or worse if was in a flying model that experienced a deep dirt injection mishap & shaft is slightly bent.

If the drive washer is aluminum & rests on either a tapered brass split cone or the steel shaft itself, then some gentle heat can be your friend. Aluminum expands more, helps break down oily mung, put the puller tool on, a quick crack & hopefully off she comes. Good luck!

In nearly 50 years of dismantling model engines of essentially all sizes I've never used (or needed) a hub-puller to remove a prop driver that was retained with a split-taper collet. All it ever needs is a sharp tap. If it has a seperate front housing just put it back into the crankcase and place the back of the crankcase (backplate removed) on a flat wooden surface. Then just sharply tap the end of the crankshaft with a small hammer (either one with brass/nylon faces or with a piece of beach, aluminium or nylon between the two to protect the thread). The collet will separate easily, and nothing gets bruised. This method obviously works well with one-piece crankcases as well.

To be honest, with my race engines I could generally get the prop drivers to release by just tapping the front of the shaft smartly on the bench, but this takes practice to get right. But if you don't want to use a hammer you can also put the backplateless crankcase unto a vice between wooden jaws (back of the crankcase squarely on one jaw, tip of the crankshaft squarely against the other) and gently press the shaft through the collet so that it releases, but this method (like using a puller) runs the risk that the collet slides along without releasing its grip on the propdriver.

I don't like using hub-pullers on propdrivers - they are too gentle and very prone to bending/damaging the driver so that it's no longer true to the shaft. Also as the push rather than pull against the front of the crankshaft they have a strong tendency to move sideways, which can bend or even snap the front of the shaft. They may be good for flywheels, but I wouldn't use one on a prop-driver - YMMV